Hand held electronic devices such as mobile telephones, cordless telephone handsets, hand-held computers, calculators, remote controls, portable game consoles, and the like, often employ keypads for entry of information and commands. Most modern high end smart phones are shipped with touch screens, utilizing the Liquid Crystal Displays (referred to hereinafter as “LCDs”) to display any combination of keys, in any shape, in any color and in any brightness. Low cost input devices, due to the cost consideration may not have LCD touch pads as input devices. However, most of the hand held electronic devices in the market today, including low end or low cost products, may no longer be confined to the conventional four by three grid numeric keypad grids, such as the half QWERTY or full QWERTY keypads. Even at the low end, the freedom and flexibility of having any shape, color, or key combination, similar to LCD touch pads, may become standard in future input devices.
An input device may adopt a capacitive sensing approach. Usually an input device may have a printed circuit board (referred to hereinafter as “PCB”) adapted to sense touching or pressing on a key plate member. The key plate member may be a semi-transparent plate backlit by a light guide similar to those from an LCD screen. The light guide may be flexible and thin. By having multiple light guides and multiple light sources coupled to the light guides, the keypad may be illuminated partially and independently by the light sources to display specific colors on specific portions of the key plate member.
Illumination schemes are no longer as simple as “light on” or “light off” across an entire four by three grid numerical keypad. The advance of technology in light guide area enables more flexibility in the designs of many input devices, such as the remote control input pads, security input pads, mobile phones, game consoles and other similar electronic devices. While the advancement in input devices is attractive, the assembling or manufacturing process of input devices is becoming more complicated and more expensive, adding to the expense of many electronic devices themselves. For example, an input device that is divided into ten zones of light segments may require up to ten pieces of light guide to be assembled instead of one. If the shape of a particular light guide is irregular, the assembly process may become even more complicated and expensive.
Yet, market conditions are demanding ever more symbols and characters to be squeezed onto a keypad with more light segments being illuminated independently. Therefore, it may be desirable to have an input device, a keypad, or even a light guide with multiple light segments to enable design flexibility. However, market conditions are continuing to push for simplified assembly processes and less expensive electronic devices.